This invention relates to a supercharger.
In superchargers which have heretofore been employed, the lubricant supplied through an inlet port is fed to a thrust bearing and a journal bearing, and the leakage of the lubricant to the turbine side is prevented by an oil seal mounted on the turbine side. An engine blow-by pressure is exerted on the inside of a center housing through a lubricant outlet pipe. Further, because the clearance between a turbine impeller and a heat shroud is comparatively small, the part of the turbine impeller near a seal ring tends to be subjected to a pressure much lower than the gas pressure at the turbine inlet.
In the case the supercharger is driven under such condition for a long time, the lubricant to lubricate the seal ring tends to leak through the back surface of the turbine impeller towards the inside of the turbine casing and the parts joining the center housing and the turbine casing thereby causing fire hazards or forming carbon deposits therebetween to give bad influence on the supercharger itself.